Orthogonal Frequency Division Multiplexing (OFDM) is an attractive transmission scheme for wireless systems to achieve high data rates. It has been widely adopted in different wireless standards, e.g., DVB-T/H, ISDB-T, IEEE 802.11a/g/n. With an appropriate guard interval, OFDM provides a spectrally efficient transmission scheme that is robust to the multipath spread of the wireless channel by a simple equalization.
Although the robustness against multipath effects and high spectral efficiency are advantages of OFDM systems, the OFDM systems are sensitive to mobility, i.e. the transmission of an OFDM signal from a non-stationary transmitter and/or the reception of the OFDM signal by a non-stationary receiver. Since mobility results in Doppler spreading, it leads to the loss of orthogonality among the subcarriers known as inter-carrier interference (ICI). If not compensated, ICI hampers the reception at the mobile terminals for instance because ICI increases the bit error rate (BER) in a processed signal.
Antenna selection is one of the simplest and most effective ways of obtaining diversity in receivers comprising multiple spatially separated antennas for receiving the OFDM signal through different channels. Since each channel consists of a different set of multiple paths, a channel can be selected in which the signal-to-noise ratio (SNR) is maximized within the set of antennas.
Receive antenna selection mechanisms are especially popular due to their ease of implementation without the need to change the communication standard. Several antenna selection mechanisms have been investigated for conventional multiple receive antenna systems, MIMO systems. In “Some Elementary Suboptimal Diversity Reception Schemes For DVB-T in Mobile Conditions” by Jukka Rinne in IEEE Transactions on Consumer Electronics, 46(3), 2000, pages 847-850, an SNR-based receive antenna selection mechanism for mobile OFDM systems is discussed.
In time-invariant channels, receive antenna selection provides spatial diversity and mitigates the effects of fading. However, in time-varying channels, conventional SNR based antenna selection has limited capability since the interference, i.e. the Doppler spreading, which determines the performance of mobile OFDM systems is not considered in these conventional antenna selection processes.